Airtel — got msg twice that twenty rupees get deducted even though I haven't used any

I am using ur sim for about 4 years but i hadnt faced any problem up to now. thanks for your service. but in the last two months i am getting mszs as already said in the subject.first i got a msz saying 20rs got deducted on 28-8-18 for using bakthi sagar portrait after a month again 20rs got deducted on 17-9-18- for using prime zone. i havent used any service. please consider my complait & refund my money i.e Rs.40.

hoping for quick and positive response.

thank you